EP4201391A1 - Construction multicouche - Google Patents

Construction multicouche Download PDF

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Publication number
EP4201391A1
EP4201391A1 EP21217466.8A EP21217466A EP4201391A1 EP 4201391 A1 EP4201391 A1 EP 4201391A1 EP 21217466 A EP21217466 A EP 21217466A EP 4201391 A1 EP4201391 A1 EP 4201391A1
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EP
European Patent Office
Prior art keywords
shaped body
weight
powder
layers
sintered
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
EP21217466.8A
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German (de)
English (en)
Inventor
Michael GÖDIKER
Christopher NEUN
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Vita Zahnfabrik H Rauter GmbH and Co KG
Original Assignee
Vita Zahnfabrik H Rauter GmbH and Co KG
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
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Publication date
Application filed by Vita Zahnfabrik H Rauter GmbH and Co KG filed Critical Vita Zahnfabrik H Rauter GmbH and Co KG
Priority to EP21217466.8A priority Critical patent/EP4201391A1/fr
Priority to PCT/EP2022/086277 priority patent/WO2023117732A1/fr
Publication of EP4201391A1 publication Critical patent/EP4201391A1/fr
Pending legal-status Critical Current

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    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/818—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising zirconium oxide
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/822—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising rare earth metal oxides
    • A—HUMAN NECESSITIES
    • A61—MEDICAL OR VETERINARY SCIENCE; HYGIENE
    • A61K—PREPARATIONS FOR MEDICAL, DENTAL OR TOILETRY PURPOSES
    • A61K6/00—Preparations for dentistry
    • A61K6/80—Preparations for artificial teeth, for filling teeth or for capping teeth
    • A61K6/802—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics
    • A61K6/824—Preparations for artificial teeth, for filling teeth or for capping teeth comprising ceramics comprising transition metal oxides
    • B—PERFORMING OPERATIONS; TRANSPORTING
    • B32—LAYERED PRODUCTS
    • B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
    • B32B18/00—Layered products essentially comprising ceramics, e.g. refractory products
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    • C04B35/00—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products
    • C04B35/01—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics
    • C04B35/48—Shaped ceramic products characterised by their composition; Ceramics compositions; Processing powders of inorganic compounds preparatory to the manufacturing of ceramic products based on oxide ceramics based on zirconium or hafnium oxides, zirconates, zircon or hafnates
    • C04B35/486—Fine ceramics
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    • C04B35/626—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B
    • C04B35/63—Preparing or treating the powders individually or as batches ; preparing or treating macroscopic reinforcing agents for ceramic products, e.g. fibres; mechanical aspects section B using additives specially adapted for forming the products, e.g.. binder binders
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    • C04B2235/3225—Yttrium oxide or oxide-forming salts thereof
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    • C04B2235/327—Iron group oxides, their mixed metal oxides, or oxide-forming salts thereof
    • C04B2235/3275—Cobalt oxides, cobaltates or cobaltites or oxide forming salts thereof, e.g. bismuth cobaltate, zinc cobaltite
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    • C04B2235/5418—Particle size related information expressed by the size of the particles or aggregates thereof
    • C04B2235/5436—Particle size related information expressed by the size of the particles or aggregates thereof micrometer sized, i.e. from 1 to 100 micron
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Definitions

  • the present invention relates to a sintered shaped body with color gradient for use in the production of dental restorations obtainable by sintering a pressed shaped body comprising 2 or more differently colored ceramic powder layers and a method for its production and the use of the shaped body for the production of dental restorations.
  • Zirconium dioxide ceramics have found their way into dental technology for the production of dental restorations due to their hardness and good machinability as well as their controllable translucency properties.
  • ZrO2 ceramics are usually colored by adding coloring oxides, which are sintered together with the zirconium dioxide.
  • coloring oxides which are sintered together with the zirconium dioxide.
  • the problem here is that the coloring metal oxides can have an influence on the sintering behavior of the zirconium dioxide ceramics. This was found in particular when using iron oxides.
  • the object of the present invention is therefore to provide a sintered shaped body which solves the aforementioned problems, in particular which can be sintered without distortion over a large temperature range.
  • the subject matter of the present invention in a first embodiment is a sintered molded body with a color gradient for use in the production of dental restorations, obtainable by sintering a pressed molded body comprising 2 or more ceramic powder layers of different colors, each powder layer having at least 80% by weight ZrO 2 and essentially is free of iron oxide, characterized in that at least one powder layer has terbium oxide.
  • essentially free of iron oxide means that less than 0.01% by weight, preferably less than 0.001% by weight or less than 0.0001% by weight, based in each case on the total weight of the powder layer, is present .
  • the sintered shaped body is free from iron oxide.
  • terbium oxide has proven to be excellent for coloring and warpage stability.
  • terbium oxide basically includes all oxides of terbium.
  • the terbium oxide is selected from the group consisting of Tb 2 O 3 , Tb 4 O 7 , Tb 7 O 12 , Tb 11 O 20 , TbO 2 and mixtures thereof.
  • Terbium oxide selected from the group consisting of Tb 4 O 7 , Tb 7 O 12 , Tb 11 O 20 and any mixtures thereof can be used with particular preference.
  • the terbium oxide is particularly preferably present as Tb 4 O 7 or as a mixture of Tb 4 O 7 with Tb 7 O 12 and/or Tb 11 O 20 .
  • Terbium oxides present with mixed valence are also preferred.
  • a preferred embodiment comprises at least one powder layer, preferably at least 2 powder layers or at least 3 powder layers or at least 4 powder layers, especially 5 powder layers or each powder layer Terbium oxide in an amount of 0.001 to 0.15% by weight, preferably 0.01 to 0.1% by weight, in particular 0.02 to 0.06% by weight terbium oxide.
  • each of the sintered powder layers exhibits an essentially equal change in volume over a temperature range of 25 to 1600 °C, in particular over a temperature range of 50 to 1400 °C or 900 to 1400 °C and especially over a temperature range of 900 to 1350 °C.
  • a substantially equal change in volume means that the difference in the change in volume at a predetermined temperature in the range from 25 to 1600° C. of 2 layers of the sintered blank according to the invention is at most 1%, preferably at most 0.5%, in particular at most 0.05%. amounts to.
  • each powder layer has a different concentration of terbium oxide, erbium oxide and cobalt oxide.
  • each powder layer has only terbium oxide, erbium oxide and cobalt oxide as coloring metal oxides.
  • each powder layer has terbium oxide, erbium oxide and cobalt oxide but is essentially free of other coloring metal oxides.
  • Essentially free of other coloring metal oxides in the context of the present invention means that less than 0.01% by weight, preferably less than 0.001% by weight or less than 0.0001% by weight, based in each case on the total weight of the Powder layer is present.
  • the sintered shaped body is free from other coloring metal oxides.
  • At least one powder layer particularly preferably 2 or more powder layers, in particular each powder layer, has erbium oxide (Er 2 O 3 ) in an amount of 0.1 to 1.0% by weight, especially 0.2 to 0.8% by weight. %, each based on the total weight of the powder coating composition.
  • erbium oxide can be used in the amounts used as coloring metal oxide without adversely affecting the sintering properties.
  • the weight ratio of terbium oxide to cobalt oxide in at least one powder layer is in the range from 80:1 to 5:1, preferably 75:1 to 10: 1 and specifically 60:1 to 15:1.
  • good color and sintering properties could be achieved with the aforementioned set weight ratios, especially when using Tb 4 O 7 .
  • Each powder layer can be preferably prepared by mixing base powders.
  • each powder layer is produced by mixing 2 or more, preferably 3 or more, in particular 4 or more base powders.
  • the use of a limited amount of base powders in different amounts for the production of each powder layer has advantages in terms of the compatibility of the individual layers arranged one on top of the other and their color gradient in the sintered body.
  • Suitable base powders can be obtained, for example, from Tosoh.
  • the sintered shaped bodies of the present invention preferably have a gradual color gradient.
  • the blank has layers of different colors and the sintering process produces a gradual color gradient.
  • At least 2, preferably all, powder layers have an essentially identical yttrium oxide content.
  • Substantially identical yttrium oxide content in 2 or more layers within the meaning of the present invention means that the difference within the layers is not more than 0.1 mol%, preferably not more than 0.05 mol%, in particular less than 0.01 mol%.
  • the sintered shaped body has a translucency profile.
  • the shaped body according to the invention preferably shows a layered increase in the amount of yttrium oxide.
  • the shaped bodies according to the invention have powder layers each with at least 0.02% by weight Al 2 O 3 .
  • the powder layers each contain at least 0.02% by weight Al 2 O 3 , preferably Al 2 O 3 in an amount of 0.03 to 0.15% by weight, in particular Al 2 O 3 in an amount of 0.03 to 0.08% by weight.
  • the preferred amount of Al 2 O 3 in the individual powder layers leads to improved stability and strength behavior of the shaped bodies according to the invention.
  • the Y 2 O 3 has a function of stabilizing the zirconia crystal phases and is not a coloring metal oxide in the sense of the present invention.
  • the erbium oxide (Er 2 O 3 ) has a stabilizing function for the ZrO 2 crystal phases and is a coloring metal oxide within the meaning of the present invention.
  • the powder layers preferably contain zirconium dioxide and/or HfO 2 in an amount of at least 89% by weight, preferably in an amount of 89 to 98% by weight, in particular from 90 to 96% by weight, based in each case on the total weight of the components of the powder layer.
  • the powder layers comprise zirconium dioxide and hafnium dioxide, particularly preferably the amount of hafnium dioxide is 0.1 to 5% by weight, especially 0.5 to 2.5% by weight, based on the total weight of zirconium dioxide and hafnium dioxide.
  • the molded body consists of 3 or 4 or in particular 5 different ceramic powder layers.
  • the molded body consists of 5 ceramic powder layers, the first powder layer being 20 to 30%, preferably 22 to 28%, the second powder layer being 10 to 20%, preferably 12 to 18%, and the third powder layer being 15 to 25%, preferably 17 to 23%, the fourth powder layer 10 to 20%, preferably 12 to 18% and the fifth powder layer 20 to 30%, preferably 22 to 28%, of the total thickness of the superimposed powder layers and with the proviso that the total thickness adds up to 100%.
  • the sintered shaped body is first pre-sintered and processed by subtractive methods and is preferably then finally sintered in a further step.
  • the sintered moldings of the present invention are used in particular as dental restorations or for the production of dental restorations.
  • At least one powder layer preferably all powder layers, additionally has organic components, preferably in an amount of 3-6% by weight, in particular in an amount of 4-5% by weight.
  • organic components preferably in an amount of 3-6% by weight, in particular in an amount of 4-5% by weight.
  • binders and pressing aids come into consideration as organic components, which can easily be thermally removed in the debinding step.
  • Suitable binders for zirconia sinter powder are known to the person skilled in the art. This includes, for example, polyvinyl alcohol (PVA).
  • the layered powders preferably have a bulk density below 1.2 g/cm 3 .
  • layered powders which have an average granule size D 50 of 35 ⁇ m-85 ⁇ m, preferably 40 ⁇ m-80 ⁇ m and in particular 50 ⁇ m-70 ⁇ m or 40-60 ⁇ m.
  • the dry granulate powders are measured by means of laser diffraction using a Cilas granulometer.
  • the inorganic components of the base powder i.e. after removal of the organic components such as binders, etc., have a particle size D 50 of 0.1 to 1 ⁇ m, preferably 0.2 ⁇ m - 0.8 ⁇ m and in particular 0.2 ⁇ m - 0.7 ⁇ m, measured by laser diffraction. It was found that the particle sizes make a positive contribution to the sintering and in particular to the color transitions between the individual powder layers.
  • the pressed molded body to be sintered according to the invention can be obtained by arranging 2 or 3 or in particular 4 or 5 or more ceramic powder layers one on top of the other.
  • the layers can be arranged, for example, in a cylindrical container with the formation of discs or disks.
  • the powder layers can usually be pressed uniaxially. This can be done, for example, by means of a ram, but only pre-consolidation takes place.
  • the uniaxial pressing of the layers perpendicular to the layer surface is preferably carried out at a pressure of 10-20 MPa, in particular 12-15 MPa.
  • the ceramic powder layers arranged in layers one on top of the other are pressed to form a molded body by pressing initially uniaxially and perpendicularly to the layer surface, preferably with the formation of a pre-compacted molded body with a density below 2.8 g/cm 3 , preferably having a density in the range 2.5-2.7 g/cm 3 e.g. 2.65 g/cm 3 .
  • the uniaxial pre-compaction can lead to a better and more intimate mixing and thus an even transition between the layers.
  • the pressing to produce the pressed molded body takes place isostatically, with the isostatic pressing preferably taking place after uniaxial precompression, with the formation of a pressed molded body having a density below 3.4 g/cm 3 , in particular a density of 2.80 - 3.3 g/cm 3 , especially with a density of 2.85 - 3.25 g/cm 3 .
  • Isostatic pressing is preferably performed after all layers of the compact are placed. Suitable pressures for isostatic pressing are usually in the range of 500-10000 bar, preferably in the range of 800-8000 bar, for example 1000-7000 bar or 1000-3000 bar.
  • the thicknesses of the individual powder layers of the compact can vary.
  • at least two of the ceramic powder layers differ in terms of their thickness.
  • at least two of the ceramic powder layers of the compact have a thickness difference of at least 5%.
  • the compacts may be in the form of cylindrical, circular discs with diameters in the range 50 to 200mm, for example 75 to 150mm.
  • the total thickness of the cylindrical disks can be, for example, in the range from 8 to 40 mm, preferably from 10 to 30 mm, especially from 13 to 25 mm.
  • the dimensions refer to the molded body in the unsintered state.
  • At least one of the outer ceramic powder layers preferably both outer ceramic powder layers of the molded body, has/have a greater thickness than a ceramic powder layer lying between the outer ceramic powder layers.
  • the layer structure described above with at least one thicker outer layer has proven to be advantageous, since this represents a suitable structure for processing in CAD/CAM systems or other subtractive processing methods.
  • the molded body comprises five ceramic powder layers, the first powder layer being 20-30%, preferably 22-28%, the second powder layer being 10-20%, preferably 12-18%, and the third powder layer being 15-25% %, preferably 17 - 23%, the fourth powder layer 10 - 20%, preferably 12 - 18% and the fifth powder layer 20 - 30%, preferably 22 - 28% of the total thickness of the superimposed powder layers and with the proviso that the Added total thickness to 100%.
  • the sintering takes place at a temperature in the range from 950 to 1100° C., preferably from 980 to 1050° C., with the formation of a pre-sintered ceramic shaped body (white body).
  • a pre-sintered ceramic shaped body white body
  • sintering occurs for a period of time sufficient to remove the binders present and to provide the compact with sufficient strength for processing by subtractive methods.
  • the pre-sintered and debindered compacts are referred to as white compacts.
  • the sintering to produce the white body takes place over a period of more than 30 minutes, preferably more than 1 hour, in particular more than 20 hours or more than 50 hours, for example 60 to 200 hours or 70 to 150 hours.
  • the pre-sintered ceramic shaped body is processed by subtractive methods and preferably then finally sintered in a further step.
  • subtractive methods the sintering shrinkage is usually taken into account.
  • Final sintering usually takes place at temperatures above 1350°C, preferably above 1400°C, specifically in the range from 1420°C to 1600°C or 1450°C to 1590°C or 1480 to 1580°C.
  • the sintering time for the final sintering usually takes place over a period of more than 4 minutes, preferably more than 5 minutes, in particular in the range from 5 to 120 minutes.
  • the moldings according to the invention can be used in particular in the dental field. Here they are characterized by a high edge strength in dental restorations, an excellent structure and a high 3-point bending strength.
  • the ceramic moldings of the present invention are therefore preferably dental restorations, such as inlays, onlays, crowns, bridges or veneers.
  • a further object of the present invention is the use of the ceramic molding according to the invention for dental restorations or for the production of dental restorations.
  • a further object of the present invention is the use of a base powder comprising zirconium dioxide and terbium oxide, in particular Tb 4 O 7 , and yttrium oxide for the production of sintering distortion-free ceramic dental restorations, preferably with a color gradient.
  • the base powder preferably comprises yttria in an amount of 5 to 8 wt%, preferably 6 to 7 wt%, terbium oxide in an amount of 0.1 to 0.4 wt%, preferably 0.1 to 0.3 wt% % by weight and zirconium dioxide in an amount above 80% by weight, preferably from 82% by weight to 94% by weight, especially from 84% by weight to 90% by weight, in each case based on the total weight of the base powder.
  • Another object of the present invention is a sintered shaped body with a layer structure and color gradient for use in the production of dental restorations, the shaped body having at least three different ceramic powder layers and each layer consisting of at least three or four different base powders, each base powder containing at least 80 % by weight of ceramic oxides, the weights being based in each case on the total weight of the base powder.
  • the ceramic powder layers preferably have ceramic oxides as defined above.
  • the base powders to be used correspond to the base powders defined above.
  • Table 1 shows 5 base powders A to E used for the compositions of the ceramic powder layers.
  • the granule size D 50 of Base powder is in the range of 40-80 ⁇ m.
  • the inorganic components of the base powder have a particle size D 50 of 0.2 to 0.7 ⁇ m.
  • the weight data relate in each case to the total weight of the powder composition.
  • the layer arrangements shown in Table 2 below show the composition of each ceramic powder layer in the compact.
  • the molded bodies are intended for use in the manufacture of dental restorations, so that the layer compositions are designed according to the position in the tooth.
  • the compositions of the powder layers are formed from the base powders by varying the proportions in order to obtain an ideal color gradient.
  • the composition of each powder layer is obtained by homogeneously mixing the base powders in the specified amounts.
  • the powders are then placed in layers in a cylindrical compression mold with a diameter of 100 mm and a layer thickness of 18 mm is set.
  • the powder layers are pre-pressed uniaxially at a pressure of 13 MPa perpendicular to the layer surface and then pressed isostatically at a pressure of 2000 bar.
  • Debinding then takes place at approx. 1000 °C over a period of approx. 100 hours.
  • the white bodies obtained in this way are milled into dental restorations using CAD/CAM systems.
  • the ceramic powder layers are arranged in such a way that layer 1 (incisal) 25%, layer 2 (dentin/incisal) 15%, layer 3 (dentin) 20%, layer 4 (dentin/neck) 15% and layer 5 ( Neck) accounts for 25% of the total thickness of the molded body.
  • the embodiments according to the invention that are colored with terbium oxide are distortion-free across all layers and the degree of sintering is therefore also homogeneous across all layers, which in turn leads to a homogeneous distribution of the Vickers hardness and thus also to consistent machining properties in the CAM machining.
  • figure 1 shows exemplary dental restorations that are obtained from the exemplary ceramic molded body. Shown are 2 anterior crowns.
  • the layer transitions and color transitions are fluid.
  • the restorations show excellent edge strength and stability. Reworking and readjustment of the tooth color is not necessary.
  • the optimal structure and composition of the layers shows a largely homogeneous shrinkage across all layers during sintering. This is particularly advantageous for the precise manufacture of dental restorations, as time-consuming reworking can be largely avoided.
  • Table 3 shows examples of different VITA classical A1-D4 ® tooth shades that can be created with the base powders.
  • Table 3 shows examples of different VITA classical A1-D4 ® tooth shades that can be created with the base powders.
  • Table 3 shows examples of different VITA classical A1-D4 ® tooth shades that can be created with the base powders.
  • the listed weight amounts are made up to 100% by weight with the binder and the zirconium dioxide.
  • the powder compositions for the individual powder layers of the sintered shaped body according to the invention are obtained by mixing the base powders.
  • the total weight per block is 40g.
  • the different shifts break down as follows, as shown in Tables 6 and 7:
  • the green compact density of the pressed blanks is 3.08 g/cm3.
  • the white compact density of the green compacts from which the binder has been removed is 3.17 g/cm 3 .
  • the Vickers hardness of the sintered bodies according to the invention is particularly surprising. While the Vickers hardness of the pre-sintered blank (white body) with sintered bodies not according to the invention increases with increasing Fe2O3 content, the Vickers hardness of approx. 55 HV 2 over the entire block in the sintered bodies according to the invention remains unchanged.
  • the variant with the higher yttrium content (Table 8) in the incisal (base powder E) offers a slightly higher translucency along the incisal edge.

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  • Chemical & Material Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Ceramic Engineering (AREA)
  • Health & Medical Sciences (AREA)
  • Oral & Maxillofacial Surgery (AREA)
  • Manufacturing & Machinery (AREA)
  • Plastic & Reconstructive Surgery (AREA)
  • Inorganic Chemistry (AREA)
  • Animal Behavior & Ethology (AREA)
  • General Health & Medical Sciences (AREA)
  • Public Health (AREA)
  • Veterinary Medicine (AREA)
  • Organic Chemistry (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Structural Engineering (AREA)
  • Epidemiology (AREA)
  • Materials Engineering (AREA)
  • Composite Materials (AREA)
  • Crystallography & Structural Chemistry (AREA)
  • Dental Preparations (AREA)
EP21217466.8A 2021-12-23 2021-12-23 Construction multicouche Pending EP4201391A1 (fr)

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EP21217466.8A EP4201391A1 (fr) 2021-12-23 2021-12-23 Construction multicouche
PCT/EP2022/086277 WO2023117732A1 (fr) 2021-12-23 2022-12-16 Structure multicouche

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP3108849A1 (fr) * 2016-04-25 2016-12-28 3M Innovative Properties Company Ébauche pour fraisage dentaire à zircone multicouche et procédé de production
DE102016106370A1 (de) * 2016-03-23 2017-09-28 Degudent Gmbh Verfahren zur Herstellung eines eingefärbten Rohlings sowie Rohling
WO2018115529A1 (fr) * 2016-12-23 2018-06-28 Ivoclar Vivadent Ag Corps multicouche en céramique oxydée présentant un comportement au frittage adapté
EP3772497A1 (fr) * 2019-08-08 2021-02-10 VITA-ZAHNFABRIK H. Rauter GmbH & Co. KG Lingot de zircone à dégradé de couleur ou de translucidité

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE102016106370A1 (de) * 2016-03-23 2017-09-28 Degudent Gmbh Verfahren zur Herstellung eines eingefärbten Rohlings sowie Rohling
EP3108849A1 (fr) * 2016-04-25 2016-12-28 3M Innovative Properties Company Ébauche pour fraisage dentaire à zircone multicouche et procédé de production
WO2018115529A1 (fr) * 2016-12-23 2018-06-28 Ivoclar Vivadent Ag Corps multicouche en céramique oxydée présentant un comportement au frittage adapté
EP3772497A1 (fr) * 2019-08-08 2021-02-10 VITA-ZAHNFABRIK H. Rauter GmbH & Co. KG Lingot de zircone à dégradé de couleur ou de translucidité

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